Il-lB is a key molecule in immunologic as well as inflammatory processes and is thought to be the major mediator stimulating bone loss in periodontal and arthritic diseases. The receptor proteins for Il-lB have been cloned and named Il-1 type I and type II receptors (Il-lRI, Il-lRlI) and Il-l receptor accessory protein (Il-lRAcP). The goal of these studies is to better understand the signal transduction mechanisms of Il-lB. To this end, various mutant cDNA constructs are being developed for eukaryotic transient transfection assays. Different dominant negative and positive expression systems will be tested to dissect out complex protein-protein interactions and activation of known gene transcription factors. It is hoped that understanding signal transduction of Il-lB may lead to improved therapeutic approaches to degenerative inflammatory diseases.